Web pick-up

ABSTRACT

THIS RELATES TO THE TRANSFER OF A MOIST PAPER WEB FROM ONE POROUS BELT TO ANOTHER, SPECIFICALLY, FROM A PAPER MACHINE FORMING WIRE TO A PICK-UP FELT. THIS IS DONE BY URGING A PICK-UP FELT (WRAPPING A PICK-UP ROLL) INTO CONTACT WITH THE WEB ON THE WIRE UNDER PRESS NIP CONDITIONS WHICH ARE AFFORDED BY THE USE OF A GROOVED PRESS ROLL BACKING THE FORMING WIRE AT THE WEB PICKUP. IN ORDER TO OBTAIN THE MOST FAVORABLE CONDITIONS FOR APPLYING NIP PRESSURE AND THEN CARRYING THE WEB AWAY FROM THE WIRE ON THE PICK-UP FELT THE GROOVED ROLL USED HAS A RELATIVELY SMALL RADIUS (AND MAY BE CROWNED TO KEEP THE WIRE SPREAD).

. RDNHN WEB PICK-UP 2 SheetSSheet l Filed Nov. l5, 195'? NVENTOR.

EXTORNISYS WEB PICK-UP 2 Sheets-Sheet 2 Filed Nov. l5, 1957 INVENTOR.

United States Patent 3,595,745 WEB PICK-UP Dennis Callahan Cronin,Rockton, Ill., assignor to Beloit Corporation, Beloit, Wis. Filed Nov.15, 1967, Ser. No. 683,168 Int. Cl. D21f 2/00 U.S. Cl. 162--306 10Claims ABSTRACT F THE DISCLOSURE This relates to the transfer of a moistpaper web from one porous belt to another, specifically, from a papermachine forming wire to a pick-up felt. This is done by urging a pick-upfelt (wrapping a pick-up roll) into contact with the web on the wireunder press nip conditions which are afforded by the use of a groovedpress roll backing the forming wire at the web pickup. In order toobtain the most favorable conditions for applying nip pressure and thencarrying the web away from the wire on the pick-up felt the grooved rollused has a relatively small radius (and may be crowned to keep the wirespread).

This invention relates to the papermaking art, and more particularly, tothe solution of certain problems arising in the papermaking art byvirtue of the higher machine speeds that are desirable for production atthe present time.

It is well known in the art that the moist fibrous web of paper is firstformed by deposition of stock onto and with drainage of water from thestock through a so-called forming wire which may be a nely wovenmetallic screen-like or fabric porous belt, or it may be a finely wovenplastic fabric defining a porous forming belt. While the moist newlyformed web travels on the forming wire, it is in relatively -delicatecondition and it must be handled with a certain amount of care in orderto avoid permanent damage to the resultant paper web. In this respect,it is usually difiicult to effect a removal of the newly formed moistweb from the forming wire under the relatively high speed conditions ofpresent-day operation.

Web pick-up (from the forming wire) has been conducted in various waysheretofore; but in general, the procedure involves the use of atraveling porous belt usually called the pick-up felt, which wraps apick-up roll that urges the traveling pick-up felt into contact with themoist web on the wire. As the pick-up roll rotates with the pickup feltwrapped thereabout, the pick-up felt is guided away from the formingwire and it carries the moist web with it away from the wire. Thepreferential attraction of the moist web for the pick-up felt may behelped considerably `by the use of a suction area in a conventionalsuction roll structure used as the pick-up roll. Alternatively, a ratherheavy wet felt may be used with a solid pick-up roll, and the relativelyair impermeable moist felt wrapping the plain pick-up roll will tend toeffect a pumping type of action for holding the web onto the undersideof the felt at the off-running side of the web pickup station.

It will be appreciated that any pumping or vacuumtype of device tendingto pull the web away from the forming wire (and cause it to adhere tothe off-running pickup felt) will also have the tendency to cause asurge of water to fiow from the underside of the forming wire backthrough the forming wire and in the direction of the web being pickedup. This particular phenomenon is governed to a substantial extent bythe rate of felt expansion at the off-running side of the web pickup. lfthe felt expansion is too slow, then the surge of water may beinsutiicient to free the fibers of the web tending to cling mail to thewire. On the other hand, if too great a surge or too prolonged a surgeof water travels through the wire and sprays against the web at theoff-running side of the pickup station, then there is a tendency tocause other damage to the web. This latter situation may also occur inan undesirable manner if the web leaves the forming wire too graduallyor at too close an angle, such as might result from pressing the pickupfelt too hard against the web on the tensioned but yielding forming wirerun.

The instant invention provides a solution for a number of problems justmentioned, particularly in connection with high speed operation. In theinstant invention, there is provided a relatively small grooved pressroll which is mounted against the back side of the forming wire at theweb pickup station and which permits the development of relatively highnip pressures at the web pickup station. Because such grooved roll isprovided with a press surface having a plurality of alternatingcircumferential lands and grooves, it readily permits the flow of waterfore and aft through such grooves and avoids tendencies to build upwater at a nip in the location of web pickup. On the other hand, theflow of water through the grooved roll is such that it will not precludethe presence of a ldesired amount of water at the immediate off-runningside of the nip defined thereby in order to effect the requisite surgingor flow of water to help release the web from the wire at theoff-running side of the web pickup station.

Other objects, features and advantages of the present invention willbecome apparent to those skilled in the art from the following detaileddisclosure thereof and the drawings attached hereto and made a parthereof.

On the drawings:

FIG. 1 is an essentially schematic elevational view of one embodiment ofthe instant invention;

FIG. 1A is a fragmentary enlarged detail sectional view takensubstantially along the line A-A of FIG. 1;

FIG. 2 is an essentially schematic elevational view of anotherembodiment of the instant invention; and

FIG. 2A is a fragmentary enlarged detailed cross section takensubstantially along the line A--A of FIG. 2.

As shown on the drawings:

In FIG. l there is shown a paper machine pickup area indicated generallyby the reference numeral 10, including a forming wire 11 traveling overa couch roll 12 through a downwardly inclined generally uniplanar run11a around a turning roll 13 and back through a return run 11b tocomplete the loop of the forming wire 11. The forming wire 11 carries afreshly' formed moist paper web W over the couch roll 12 and down thedownwardly inclined but generally uniplanar run 11a to a pickup nip N-1that is defined between a grooved press roll 14 and a plain pickup roll15 wrapped by a moist pickup felt 16 The pickup felt 16 is here showntraveling around an upper guide roll 17 and then around the pickup roll15, at which it picks up the web W along its underside at the pickup nipN-1 and carries the same to a first press nip N-2 which is defined by abottom plain roll 18 and a top grooved roll 19. The felt 16 travels fromthe press nip N-2 around a plurality of guide rolls 20, 21, 22 and 23and a tension roll 24, and in so traveling the felt 16 is exposed towater showers S and is pressed and reconditioned at a nip N-4 between apair of grooved rolls 19 and 25 which serve to clean and recondition thefelt 16 and prepare it to return around the guide roll 17 and pickuproll 1S to the pickup nip N-1.

The travel of the web W here involved includes travel along theunderside of the felt run 16a from the pickup roll 15 to the first pressnip N-Z, where the web W is dewatered and tends to stick temporarily tothe plain bottom press roll 18, but the web W separates from thedown-running side of the press roll 18 and travels around"a'conventional guide roll 27 and into a second press nip N-3 defined bya top plain roll 28 and a bottom grooved roll 29 wrapped by a press felt30 which is shown traveling over guide rolls 31 and 32. At the secondpress nip N--S the web W is further dewatered and again tends to followtemporarily the plain press roll 28 at the off-running side of the pressnip N-3.

VThe grooved press rolls 19, and 29 just referred to in connection withthe web press nips N-2 and N-3 and the felt reconditioning nip N-4 arepress rolls which are v4described in considerable detail in E. I. JustusU.S. Pats.

`to the embodiment shown in FIG. 1l of Justus U.S. Pat.

No. 3,198,696 shows a press arangement having a con- `siderable amountof functional similarity to the arrangevmentfor the press nips N-Z, N-3and N-4 of FIG. 1 (in that the nips, respectively, N-11, N-13 and N-12of FIG. l1 of said patent will correspond substantially in operation andfunction to the nips N-Z, N-3 and N-4 of the instant FIG. l).

It will be seen that the instant pickup arrangement, however, differsconsiderably from the prior art. The felt 16 used in the pickup nip N-lwith the plain pickup roll 15 here shown is a comparatively heavy moistfelt which has practically no air-permeability in its moist condition sothat the felt 16 not only causes the web W to adhere to the undersidethereof while it wraps the plain pickup roll 15 (and while it expands tocreate an internal partial vcauum at the immediate off-running side ofthe pressure area in the nip N-l), but the felt 16 carries the webadhered to the underside thereof for the comparatively short distance tothe first press nip N-Z, primarily by virtue of the fact that thesubatmospheric pressure generated within the felt 16 and along thecontiguous faces of the felt 16 and the web W is not lost sufficientlyto permit the web to separate them from the felt 16 during the felt run16a from the pickup roll 15 to the press nip N-2.

Another feature of the instant arrangement involves the positioning ofthe guide roll 17 generally upstream to the pickup roll 15 so that theguide roll 17 may feed a felt run 16b into the pickup nip N-1 with aminimum of travel approaching the nip N-1 in contact with the pickuproll 15 and in a run 16b which is generally at a relatively small angleto the downwardly inclined substantially uniplanar `forming Wire run11a, which will be seen as being generally aligned With what might beconsidered a common tangent line T for the two nip-defining rolls 14 and15. The reason for the function and position of the guide roll 17 isthat the moist essentially air-impremeable felt 16 is inclined to entrapa certain amount of air during its travel, and if such trapped air israpidly expressed from the web felt (e.g. in the direction of the moistweb) it may cause a damaging spray. Hence, an initial travel around theguide roll 17 to effect expulsion of whatever entrapped air might be inthe felt in this region (into the saveall 17s) is helpful, followed by acompartively more gradual con- `vergence between the moist felt and themoist web at the approach of the web pickup nip N-1, which isaccomplished by the alignment of the felt 16 over the guide roll 17along the upstream side of the pickup roll 15, so as to effectconvergence between the felt 16 and the web W through a relatively smallacute angle a (eg. here about and preferably not more than about 45 Itwill be appreciated that the small grooved roll 14 is provided withadjustable mounting means indicated diagrammatically at 14a by thedouble headed arrow for adjustably shifting the small Igrooved roll 14toward and awayfrom the pickup roll 15 at the nip N-l. The pickup roll15 is, likewise, provided with adjustable mounting means 15a (againindicated diagrammatically by the double headed arrow), so that loadingat the nip N-1 is readily controlled. It will be appreciated that theforming wire run 11a is under substantial tension (generally in theplane of the common tangent T) which is conventional for the formingwire operation. Nevertheless, in the absence of the backup grooved roll14, it is not difficult to effect a certain amount of deflection in theforming wire run 11a by urging the felt wrapped pickup roll 15thereagainst, and this type of yielding deflection of the forming wirerun 11a is generally not desirable because the web W tends to separatewith greater difficulty and/ or be damaged when it is separating fromthe forming wire run as it is carried away on the felt run 16a. The useof the grooved roll 14 serves to eliminate disadvantages of this type.Also, the grooved roll 14 has a substantialy smaller diameter than theconventional pickup roll 15, c g., here shown with about a diameter of1/2 of that of the pickup roll 15, but preferably the diameter of thegrooved roll 14' will range from about 1A to 2/a of the diameter for theconventional pickup roll 15. In this respect, it will be appreciatedthat the pickup roll 15 carries a considerable overall load with thetensioned felt wrapped thereabout and there are certain limitations asto the minimum diameter that is ordinarily permited for practicaldynamic balance and defiection in the pickup roll 15. Also, suchdiameter tends to form a comparatively unsatisfactory web pickup nipusing a prior art arrangement involving merely the pickup roll wrappedby the pickup felt.

In contrast to the prior art arrangement, the small grooved roll willhave, of course, a smaler radius and therefore a smaller loaded nipperipheral dimension at the nip N-1. In other Words, the smaller roll 14will actually govern the peripheral dimension of maximum pressure at thenip N-l; and because the radius of the roll 14 is comparatively smallthis peripheral dimension Will be comparatively small. On the otherhand, the pressure actually exerted is a function of the tension on theforming wire divided by the radius of the grooved roll, hence thesmaller the radius for the grooved roll, the greater the pressure inpounds per square inch at the nip N-1 for a given nip pressure in termsof pounds per lineal inch. Additionally, and very important from thepoint of view of the practice of the instant invention, is the fact thatthis type of small radius nip Will effect a maximum compression of thepickup felt 16 at the nip (eg. as shown in FIG. lA), with a very rapidrelease of such compression forces against the pickup felt 16 at theimmediate off-running side of the nip N-1, so that the pickup felt 16will expand rapidly, tending to rapidly create an internal partialvacuum which will not only effect an excellent retention of the web onthe underside of the felt run 16a but will also effect a brief butsubstantial surge of water flow from the grooved roll side of the wirerun 11a back through the wire run 11a to effectively lift from the wirerun 11a the entire web W including any fibers tending to cling to thewire run 11a.

The desired type of water surge for effecting rapid lifting of the web Wfrom the wire run 11a with minimum damage is achieved here, at least inpart, by the advantage of having a relatively rapid pressure release atthe offrunning side of the nip N-1 so that substantial expansion of thefelt 16 Will occur rapidly. Such rapid expansion will yalso occur in thedesired manner for the instant felt 16 because the felt 16 (with the webthereon) is not wrapped by any substantial portion of the forming wirerun 11a (as might be the case in the absence of the backup grooved roll14, when the pickup roll 15 might be causing deflection of the run 11aof the forming wire). In other words, the backup grooved roll 14 servesto maintain the wire run 11a in substantially the common tangent planefor the rolls 14 and 15 at the nip N-1 and at its immediate offrunningside. In this way there is no bending of the wire 11a so that it mayfollow the web and felt temporarily along the off-running side of thenip N-1 or the nip load line thereof (which is along the line designatedA-A in FIG. 1).

AIt will be appreciated that the grooved roll has the grooved rollstructural already described and claimed in substantial detail in theaforesaid Justus U.S. patents. Such structure in this instance involvesa metal water impermeable structural shell 14b (FIG. 1A) plus a rubbercover 14C on the outer periphery of the shell 1419 with alternat ingcircumferentially `aligned lands 14d and grooves 14e. Although the landand groove ratios and the other parameters of the dimensions relating tothe alternating lands and grooves on the grooved roll 14 `are the sameas those already described in considerable detail in the aforesaidJustus patents incorporated herein by reference, in the instantsituation the axial dimensions of the land widths are 0.08 inch and the.axial dimensions of the groove mouths are 0.02 inch, with the groovedepths being 0.1 inch in the case of the roll 14. In such situationthese very ne grooves 14e will be bridged by the relatively strongstructure of the forming wire run indicated in cross sectionschematically at 11a of FIG. 1A, but water may ow readily into thesegrooves 14e and may ow from them readily both fore and aft of the nipN-l, because there is nothing but the ambient atmosphere to afford anyresistance to the flow of water fore and aft in the grooves 14e.Preferably a saveall 14s is mounted with the grooved roll 14 with adellector blade 14x mounted for close-running skimming relation to theunderside of the wire run 11a. But the excess of water to the undersideof the forming wire run 11a at the immediate off-running side of themaximum pressure nip load line at the nip N1 is not interferred with,because a certain amount of surging of water at this instant isdesirable for assuring a complete lifting of the web W from the wire run11a.

Referring to FIG. 1A again, the web W is indicated therein as being incontact with the wire run 11a and the felt 16 is shown in substantialcompression, lying between the web W and the plain pickup roll 15. Inthe arrangement shown in FIG. 1A, which represents the maximum pressurenip load line, it will be appreciated that water will actually ow fromthe felt 16 as well as the web W through the wire 11a and into thegrooves 14e, as indicated by the dashed line arrows leading into themiddle groove in the view of FIG. 1A. On the other hand, immediatelyafter the pressure at the nip load line is relieved, the felt 16 willspring back into its normal uncompressed thickness which will be perhapstwice the dimension suggested in FIG. 1A and in this instance a partialvacuum will be created in the body of the felt 16 (still backed againstthe plain roll and there will be a tendency for a complete reversal ofthe flow of water in directions substantially exactly opposite to thoseindicated by the dashed line arrows in FIG. 1A. At this instant acertain amount of water at the underside of the wire run 11a (on thegrooved roll side) is desirable to effect the lifting of the web Wwithout damage. The grooved roll will afford this water to some extent,because the grooves therein will afford an open area of perhaps 15 to33% but the fact that the radius of the grooved roll 14 is considerablysmaller than that for the pickup roll 15 will also help materially inthis situation, because the lands 14d on the outer periphery of thegrooved roll 14 will actually separate very rapidly from the undersideof the wire 11a and this will afford a more complete `access of thewater to the underside of the wire 11a for the brief moment that such asurge of excess water is desirable. This surge of excess water willreturn under forces that are obviously no greater than ambientatmospheric pressure (absolute pressure), hence the use of nip loadpressures of substantially greater than one atmosphere at the presstransfer nip N-1 will eifectively result in a certain amount ofdewatering of the moist web W (to an extent that the return surge ofwater will not completely replace the water expressed from the web inthe felt at this nip N-1). This is `a desirable result from the point ofview of initiating dewatering of the web W as soon as is practical andalso from the point of view of not completely refilling the voids in thewet felt 16 so that the same will retain a partial vacuum orsubatmospheric pressure within its body and along the contiguous faceW16 of FIG. 1A between the web and the felt during the felt run 16a.

Still another feature of the instant invention provides for a nominalcrowning of the grooved roll 14. The actual crowning of the groved roll14 involves such modest dimensions that it cannot be shown in thedrawings; but such crowning will constitute something in theneighborhood of a slightly enlarged diameter for the middle portion ofthe roll 14. Such slightly enlarged diameter will be in the neighborhoodof perhaps an increase of 0.02 inch to 0.10 or 0.15 inch. Thus in thecase of' a 14 inch diameter for the grooved roll 14, the rubber cover ismachined down to have a dimension along the edges of the rollsubstantially 14.000 inch, but perhaps lt of the way toward the middleof the roll the diameter of the roll will show a slight crowning of14.002` and at the middle of the roll the crown will have increasedgradually to give a diameter of substantially 14.010 inch. The actualdimensions of the crowning will depend to a substantial extent upon thevarious other conditions and elements being employed, but it will beappreciated that there is a substantial amount of water entering intothe nip N-1. Since a certain amount of pressing and dewatering at thenip N-1 is now desired in the present arrangement there will be a slighttendency toward the buildup of a hydraulic wedge in the middle of thenip N-1, in spite of the availability of unrestricted passageways forthe water to flow. Also, it is important not to dellect the forming wire11a into a concave conguration, since this may lead to folding orcreasing of the forming wire 11. Hence, the crowning of the roll 14-will afford a spreading or convex transverse contour to the forming wirein the critical regions of the web pickup nip N-1. Although crowning isnot particularly useful in many of the present-day high speed machinesfor the reason that a crowned roll (even having a crown of a fewthousandths of an inch) `will have a faster peripheral speed at itscrown that it has at its edges and this type of arrangement may resultin web damage at one of the final dewatering presses. On the other hand,in the present stage of the web formation, at the web pickup nip N-1, itis found that a nominal amount of crown is not damaging to the web W perse and it is found to be helpful in many instances with respect to theoperation of the forming wire run 11a and also with respect tomaintenance of a substantially uniform nip load transversely of thepickup nip N-1 in spite of the substantial amounts of water that arebeing brought into this nip N-l1.

Referring now to FIGS. 2 and 2A, it will be seen that the pickup stationindicated generally by the reference numeral is considerably differentin structure from that shown in FIG. 1. For `one thing the pickup rollis a suction roll in this embodiment having a small high vacuum suctionarea 115!) in the immediate vicinity of the pickup nip N-100, whichsuction area 115b is followed by a larger but lower vacuum suction area115C. Instead of a plan pickup roll 15 with a comparatively heavy wetfelt 16, in the embodiment of FIG. 2 there is used a suction pickup roll115 with a lightweight felt 116 trained about guide rolls 117 and 118and a tension roll 119, which pickup felt 116 is a comparativelylightweight felt or may even be a fabric which would function more orless merely as a power fabric in carrying the web W100 the very shortdistance that the web is carried on this felt or fabric 116 from the nipN-100 to substantially the end of the suction areas 15b ad 15C, so thatthe web W100 is simply transferred from the underside of felt 116 to thetop side of a press felt wrapping a `guide and suction roll 131 having asmall suction area 131a positioned immediately downstream from andclosely spaced from the olf-running edge of the suction area 115C. Thefelts 116 and 130 need not even touch or even contact both sides of theweb W100 simultaneously. Instead, the web may be merely dropped from theupper felt 116 to the bottom felt 130, with an assist from the suctionarea 131a.

It will be appreciated that actual pressure involved in the web pickupnip N-100 is controllable and it need not be excessive. This fact, plusthe fact that the felt 116 (or fabric if desired) does not pass throughanother press nip or a true high pressure press nip of any sort makes itpossible to have a much longer `wearing life for the felt 116.Additionally, the conventional cleaning and reconditioning devicesordinarily required for felts need not be employed in the case of theinstant felt 116, or at least the cleaning and reconditioning means neednot be as drastic or need not cause as much wear on the felt 116 as isthe case for conventional press felts, because the materials which mustbe cleaned from the surface of the felt 116 are not pressed into thefelt surface by any substantial press nip loads. This affords a verygreat advantage from a practical point of View and the guide roll heredeignated 120 for the felt run 116e at the off-running side of the vwebpickup nip N-100 is mounted so that the felt run 116:1 will run veryclose to but without touching the top felt run 130a of the felt 130, andthe transfer of the web W100 from the underside of the felt run 116a tothe top side of the felt run 13051 is readily accomplished in the mannerjust described herein. The press felt 130 will then convey the web W100into the first actual press nip N200 between a top plain roll 128 and abottom grooved roll 129, from which the felt 130 exits passing over itsguide roll 132 and the web W100 also exits following briefly the plainroll 128 until it is dropped Onto a second press felt run 230:1 for apress felt 230 which is mounted on a plurality of guide rolls 231, 232,233, 234 and 235 so as to ultimately lead the web W100 into a thirdpress nip N-300 again dened by a top plain roll 228 and a bottom groovedroll 229. The web W100 travels out of the nip N-300 temporarily with theplain roll 228i and finally onto still another press felt run 330a(shown only partially mounted on guide rolls 331 and 333). The groovedrolls 129 and 229 have the same type of groove structure as that alreadydescribed in connection with the grooved roll 29 at the second press nipN-3 in FIG. l. In this respect, it will be noted that the initialtransfer to a press felt occurs without the necessity of using aso-called transfer press in the embodiment of FIG. 2A, so that theactual dewatering of the web may take place to maximum advantage in thevery first press nip N-200 in the embodiment of FIG. 2, which is stillanother distinct advantage in this arrangement.

It will also be noted from FIG. 2 that the newly formed web W-100 isbrought to the web pickup station N-100 on the forming wire 111traveling over 'a couch roll 112 and along a generally uniplanar butdownwardly inclined forming wire run 111a which ulti-mately wraps theturning roll 113 and enters into the return run 111b. Again, the suctionpickup roll 115 is mounted for movement toward and away from the webpickup nip N-100 by conventional means here represented onlyschematically at 115:1. The grooved roll 114 which is the counterpart ofthe grooved roll 14 previously described is here shown acting againstthe underside of the Wire run 111 and mounted for selective movementtoward and away from the nip N-100 and for controlled application ofpressure at the nip N-100 on a pivoted `arm 114b actuated by pneumaticmeans such as an air spring indicated at 114e. An off-running saveall114s is also employed substantially as previously discussed inconnection with the saveall 14s.

With reference to the nip load line at substantially A-A of FIG. 2,attention is directed to FIG. 2A where it is shown that the grooved roll114 is formed of a conventional structural water impervious metallicshell 114M with a machined rubber cover 114K having grooves 114e cuttherein alternating with lands 1145!, with the alternating generallycircumferential land and groove structure being the same as that alreadydiscussed in connection with- FIG. 1A. Also, the grooved roll 114 ispreferably crowned in the manner previously described, so that thesuction pickup roll shell may also be operated with a slight crown, ifdesired, to assist in its anti-deflection function. In any event, theslight crown of the grooved roll will assist in avoiding any folding orcreasing o'f the wire run '11111. The felt or fabric 116, indicatedschematically in FIG. 2A, is shown in the compressed or loaded conditionin FIG. 2A, to represent the conditions at the nip load line, and itwill be appreciated that in the case of the felt 116, such felt ispre'ferably 'a comparatively lightweight felt or, as mentioned, aplastic wire or fabric, which will not necessarily expand to any greatextent at the immediate release of the nip load pressure at the nip N-,but, as indicated in FIG. 2A the pickup noll 115 will have theconventional suction roll perforations (only one of which is indicatedat x in FIG. 2A) which afford `Huid access to the back side of the felt116 from the suction areas 115b and 115e, so that a subatmosphericpressure is maintained on the back of and actually substantiallythroughout the web 116 by the suction pickup roll 11S from the nip loadline 0f the web pickup nip N-100 on around to the end of the low vacuumsuction area 115C. In thisvway the web W100 is carried by such pressuredifferential on the underside of the felt 116 for the full peripheraldimension of these two suction areas 115b and 115C (and after this theweb W100 can conveniently drop to the press felt run 130a in the manneralready described). The substantially uniplanar run of the forming wire111a, assisted by the backup of the preferably crowned grooved roll 114makes a rapid separation from the fonming wire run 11111 possible. Suchrapid separation will necessarily cause the return surge of water fromthe underside of the forming wire run Illa to assist in lifting the webW100 completely (with those fibers which may tend to cling to the wire)at the off-running side of the nip N-100 and the resultant pressuredifferential that is created and maintained in this run of the felt 116with the web W100 thereon is accomplished under favorable conditions.

It will beappreciated that, particularly in the case of a suction pickuproll 115, the diameter of such a pickup roll should be relativelysubstantial, among other things, for the purpose of affording areasonable amount 'o'f travel on its periphery over the two suctionareas 115b and '115C so that there will be a reasonable amount ofprotected carrying of the web W100 away from the forming wire 111a.Thus, the minimum size for the suction pickup roll 115 is definitelylimited and in this case it is substantially 34 inches. In contrast, thediameter of the grooved roll 114 is preferably 16 inches in thisinstance. It will be appreciated that the advantages of the presentembodiment 'are also implemented by the arrangement which affords forthe positioning of the suction guide roll 13-1 in very close runningrelation to the olf-running side of the nip N-'100 and to the formingwire 111a and in Very close running relation beneath the pickup felt 116while it is IWrapping the suction pickup roll 115. By so positioningthis suction guide roll 131 wrapped by the rst press felt i, it ispossible to take the moist web W100 directly from the pickup stationN-100 to a full pressure initial press nip N-200, which may operate at300 pounds per lineal inch. The next press nip N4300 may then operate atperhaps 450` or somewhat higher pounds per lineal inch, and successivepress nips (not shown) may be employed, if desired. The particularadvantage here involves the minimum wear or rough use for the pickupkfelt 116 while at the same time involves minimum delay in bringing theweb W100 to a full scale high pressure press nip. These advantages areapparent from the fact that this arrangement avoids the necessity forthe use of a so-called transfer press, where the web is transferred froma pickup felt to a press felt in a press nip arrangement which involvesall of the operational difficulties and expense of an ordinary press nipbut which does not accomplish a great deal of dewatering as compared toa full scale first press nip such as the nip N-200 here shown.

I claim as my invention:

1. In a web pick-up arrangement for a paper making machine, incombination, a pick-up roll having a given diameter, a groove rollhaving a diameter about 1A to 2/3 of said given diameter, said groovedroll defining a nip with said pick-up roll, a first porous belt mountedbetween a couch roll and a turning roll and traveling substantially in acommon tangent plane for said rolls and carrying a newly formed moistweb into said nip, and a traveling second porous belt wrapping saidpick-up roll and passing through said nip to receive the web from thefirst belt and carry the web away from the nip, said grooved roll beingpositioned within the loop of said first porous belt between said couchand said turning rolls, said grooved roll being loaded against thepick-up roll at such nip to effect dewatering of the web and saidgrooved roll having a peripheral surface defined by a plurality ofgenerally circumferential alternating narrow grooves and lands, wherebysuch lands bridged by said first belt apply substantially uniformtransversely aligned pressure to said nip.

2. The machine of claim I wherein said pick-up roll is a suction rollpresenting to said nip a suction area for assisting in web transfer.

3. The machine of claim 2 wherein a second suction roll is mounted nearthe off-running side of said nip, and a traveling third porous belt iswrapped about said second suction roll and urged thereby intoclose-running relation to the pick-up felt to receive the web therefrom.

4. The machine of claim 1l wherein the grooved roll has from 1A to ofthe diameter of the pick-up roll.

5. The machine of claim ll wherein said second belt is a pick-up feltand there is provided a pair of press rolls defining a pressing anddewatering nip receiving the pick-up felt with the web thereon.

6. The machine of claim l wherein the grooved roll is crowned to imparta transverse spreading effect to the forming wire at and after the nip.

7. In a web pick-up arrangement for papermaking machines, incombination,

a looped traveling forming wire positioned to receive a. freshly formedmoist paper web and carry said web over a portion of said loop,

a couch roll positioned within the loop of said wire for guiding saidwire to a pick-up area,

a turning roll positioned within the loop of said wire for guiding saidwire away from said pick-up area,

ll said turning roll being spaced a distance away and down from saidcouch roll so as to define a downwardly inclined generally uniplanar runpath between said couch and said turning roll for travel by said wire,

a looped traveling pick-up felt positioned outside the loop of said wireand converging at a relatively small acute angle with said uniplanar runpath to Contact said web and aid in. transferring said web from saidwire to said felt,

a pick-up roll having a given diameter and being positioned within theloop of said felt at the area of contact between said felt and saidwire, and

a grooved roll having a diameter about 1%: to 2/3 of said given diameterand being positioned within the loop of said wire generally opposite tosaid pick-up roll so as to define a pick-up nip therewith said groovedroll being loaded against said pickup nip to compress said felt at saidnip and said grooved roll having a peripheral surface defined by aplurality of generally circumferentially alternating narrow grooves andlands whereby such lands bridged by said wire apply substantiallyuniformly transversely aligned pressure at said pick-up nip.

8. In a web pick-up arrangement as defined in claim 7 wherein the acuteangle between the converging felt and the uniplanar run path is lessthan about 45.

9. In a web pick-up arrangement as defined in claim 7 wherein the grooveroll is loaded against the pick-up roll with a nip load pressure ofsubstantially greater than one atmosphere.

10. In a web pick-up arrangement as defined in claim 7 wherein thegrooved roll is crowned to have about 0.02 inch to 0.15 inch greaterdiameter along a middle portion thereof.

References Cited UNITED STATES PATENTS 3,168,435 2/1965 Beachler162-272X 3,285,806 11/1966 Justus et al. 162-306 REUBEN FRIEDMAN,Primary Examiner T. A. GRANGER, Assistant Examiner U.S. Cl. XR. 162-358

